Description:

Title: Uncertainty Quantification in Unfolding Elementary Particle Spectra at the LHC

Speaker: Mikael Kuusela, U. Chicago
 

Abstract: Any measurement made at the Large Hadron Collider is smeared by the finite resolution of the particle detectors. Using the smeared observations to infer the true particle-level spectrum is an ill-posed inverse problem, typically referred to as unfolding or unsmearing. In this talk, I will first give an overview of the statistical techniques that are presently used to unfold particle spectra at the LHC. I will then focus on the very challenging problem of quantifying the uncertainty of the unfolded spectrum. I will demonstrate that techniques that are currently used at the LHC may seriously underestimate the unfolded uncertainty. I will then propose two complementary approaches for obtaining improved unfolded confidence intervals. The first approach is based on debiasing the unfolded point estimate to obtain a bias-variance trade-off that is better suited for uncertainty quantification, while the second approach imposes shape constraints that are particularly relevant for unfolding steeply falling differential cross sections. Joint work with Victor M. Panaretos (EPFL) and Philip B. Stark (UC Berkeley).

Keywords: Physics, Astronomy, HEP